Improved Gel Test for Epoxy Prepregs
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
A technique for measuring the gel time of resin powder flaked off of an epoxy prepreg which is used as an adhesive in the manufacture of multilayer printed circuit boards is disclosed. The technique comprises: alternatingly compressing the resin sample with a probe and permitting the sample to expand as the probe is retracted, accurately measuring the probe movement, timing the procedure, and defining a gel time as the point in time where the thickness of the sample ceases to increase when an attempt is made to retract the probe. The technique permits an accurate, reproducible, objective gel test. An apparatus for performing a gel test for resin powder flaked off of an epoxy prepreg or gained from a liquid epoxy varnish is seen in Fig. 1. The technique for performing a gel test is also understood with reference to Fig. 1.